dump_stack();
}
+static inline int is_cow_mapping(unsigned int flags)
+{
+ return (flags & (VM_SHARED | VM_MAYWRITE)) == VM_MAYWRITE;
+}
+
/*
* This function gets the "struct page" associated with a pte.
*
unsigned long off = (addr - vma->vm_start) >> PAGE_SHIFT;
if (pfn == vma->vm_pgoff + off)
return NULL;
+ if (!is_cow_mapping(vma->vm_flags))
+ return NULL;
}
/*
* If it's a COW mapping, write protect it both
* in the parent and the child
*/
- if ((vm_flags & (VM_SHARED | VM_MAYWRITE)) == VM_MAYWRITE) {
+ if (is_cow_mapping(vm_flags)) {
ptep_set_wrprotect(src_mm, addr, src_pte);
pte = *src_pte;
}
continue;
}
- if (!vma || (vma->vm_flags & VM_IO)
+ if (!vma || (vma->vm_flags & (VM_IO | VM_PFNMAP))
|| !(vm_flags & vma->vm_flags))
return i ? : -EFAULT;
return -EINVAL;
return insert_page(vma->vm_mm, addr, page, vma->vm_page_prot);
}
-EXPORT_SYMBOL_GPL(vm_insert_page);
-
-/*
- * Somebody does a pfn remapping that doesn't actually work as a vma.
- *
- * Do it as individual pages instead, and warn about it. It's bad form,
- * and very inefficient.
- */
-static int incomplete_pfn_remap(struct vm_area_struct *vma,
- unsigned long start, unsigned long end,
- unsigned long pfn, pgprot_t prot)
-{
- static int warn = 10;
- struct page *page;
- int retval;
-
- if (!(vma->vm_flags & VM_INCOMPLETE)) {
- if (warn) {
- warn--;
- printk("%s does an incomplete pfn remapping", current->comm);
- dump_stack();
- }
- }
- vma->vm_flags |= VM_INCOMPLETE | VM_IO | VM_RESERVED;
-
- if (start < vma->vm_start || end > vma->vm_end)
- return -EINVAL;
-
- if (!pfn_valid(pfn))
- return -EINVAL;
-
- page = pfn_to_page(pfn);
- if (!PageReserved(page))
- return -EINVAL;
-
- retval = 0;
- while (start < end) {
- retval = insert_page(vma->vm_mm, start, page, prot);
- if (retval < 0)
- break;
- start += PAGE_SIZE;
- page++;
- }
- return retval;
-}
+EXPORT_SYMBOL(vm_insert_page);
/*
* maps a range of physical memory into the requested pages. the old
struct mm_struct *mm = vma->vm_mm;
int err;
- if (addr != vma->vm_start || end != vma->vm_end)
- return incomplete_pfn_remap(vma, addr, end, pfn, prot);
-
/*
* Physically remapped pages are special. Tell the
* rest of the world about it:
* VM_PFNMAP tells the core MM that the base pages are just
* raw PFN mappings, and do not have a "struct page" associated
* with them.
+ *
+ * There's a horrible special case to handle copy-on-write
+ * behaviour that some programs depend on. We mark the "original"
+ * un-COW'ed pages by matching them up with "vma->vm_pgoff".
*/
+ if (is_cow_mapping(vma->vm_flags)) {
+ if (addr != vma->vm_start || end != vma->vm_end)
+ return -EINVAL;
+ vma->vm_pgoff = pfn;
+ }
+
vma->vm_flags |= VM_IO | VM_RESERVED | VM_PFNMAP;
- vma->vm_pgoff = pfn;
BUG_ON(addr >= end);
pfn -= addr >> PAGE_SHIFT;